SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de366aa3ddd2c38b6bbd087272b8174c90443f544a9c489a05f8af740d15a392' 
  AND token = 'VPCWtBZd72LmAoK4xdZA1wBzHWYZ8VElOwQ+7neqKAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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