SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6021060a18f9377d0169e249210d908cd0338c8fe1abf018584569e0295854c8' 
  AND token = 'v+jtntQ5ZGPZN+ByJDhSxNdJ62zmFzeOzByGx07TFM8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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