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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ebd8cbd51126571ea9b3666c3253db1605744f5eb55f641dd80f33dad52fd51' 
  AND token = 'STMYA+DEpAjDmamgMdnhjU8UbV2WBvOPeqOt+HUq9ks=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}