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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2679d1216c29df44ff9ff095f2c73ff542e2c7d0b54c7d267f813eb947049b2' 
  AND token = 'dL+9mT+DTQjnQRiuKxUkXBwotWh+ILPtvgQ2+e2g/vU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}