SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bbf8cd4b58383c6bd02111c9e321046f2d017d5915ae2187011519f146eb5c8' 
  AND token = 'fj85XBywiAClN4FwQwgbavzK8e+CkbK/uZagO/diIhc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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