SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27374b2d79d5a30bfc92e1be91ee628830e8054eed4768dce1087b375a5541d6' 
  AND token = 'FuP+bfa5LROgMj/oye/OxrwmIyT3vY4vVvMk2s6xKxA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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