SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c668086700d059e6253ea8933093a963bad7195942072e89c73b877af66571d' 
  AND token = 'MMEwhpDrwXq4+7OnPIu0YecIJ2li3cELzhImeWtHEng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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