SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dedbe6e1f13723ce12ad51311241947b82b8474a50d19c0f01b21ed46c31b79e' 
  AND token = 'slzlBDoACWvQHm08wIEEtKnopx1O4LjUREgMikibFwM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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