SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39ab03306f728e0acc5461327c492f13cd1913f7a218756dbfcf48e177565392' 
  AND token = 'zz+iK3IuzHuoDpKsLXUlBA5frJOKCMNVXTl0WCeCqsE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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