SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21e6d62817037724ccdd492dd94d9e120b18d5ef34ee33c3e90d9ef0e39c6115' 
  AND token = 'U0yxDJWMwqjENd03IVYog8Sq3RTIWGYMPmTQfyLtoLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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