SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '925a273c1a3fd82c39c562b3fabec1e6462e70c0f2b51544ae308826907ff7ce' 
  AND token = 'JpymFUPfQl0+7QGVRNDq7EzDUAwHxkSwxUVLxtnk3Z8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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