SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfb69c5f759e33791283218a946bad28367057e347bd7fe762d39d421cbafdd3' 
  AND token = 'RXP7gtaiKZVDrHlOhMxJA9am+bl+VbEXIJPT+9bsWY8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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