SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c978e847dbd7bad880874e0069c7b77f72576948223e0750cf8df618e3347293' 
  AND token = 'hYj1WIN5W5Hp+B/26MznrvBjnMjjZvTAAKKcFao6KYo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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