SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92f972265d3cccb17f3f602a4cb1210f7dde1458d40396007c3ecb73f47b5123' 
  AND token = 'kU/3nJaADUdJ9rYKiGOpR6xOGS6mY1+Vjog4zQj/p8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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