SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a71e396f7511d4101ef9a46f8a7b80e8d76144998c493ccf7ed7362e3069847' 
  AND token = 'QOZykwoPLTUR/P759ajl3ZZKlSshekKgepHDUGOET5A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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