SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af2e4107b677109bd7b47bc626897aac00a57da25c17e4428ccdafd5210ebf66' 
  AND token = 'yLjE5jh9Ar1eg3jMdwlwIuf+8Cqx/ZbPgLfHblcBiLQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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