SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c31dab768c60c4920ac944d29403af707b844a282fb2c9937e9321a961c5e05f' 
  AND token = 'FjYlk1p6VFcqK/9857roNoxmKYsIQW49sJgT+wrEH3g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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