SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39b58fc2b2b8f7a6fb32d9e292b88e4859de87f5b142239892acd33fea98561f' 
  AND token = 'niHaVnyxBdi9tBdqcLD74Y0/KvW3fpZKiQrsdJP/Y6g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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