SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'add33769dda96ad65c005dff2fde7e8f75056bebfcbb45b684bda77279d73ec0' 
  AND token = 'CMn3FKh22rc0ljqOlaC49Pp78AeSE1+Ehw5oTepqUy8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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