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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e47f3e95cc7fce364dfcb94c66fa559f25f0e2b7123c75d54ed93bdc9f69bfcb' 
  AND token = 'bUNW6LvMbvsZDuj6DquZ0SFMxrZFdLP5sNA5LOvQ9tQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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