SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15ceb378b77939cb2d004f7200f6bab9ac6ca42c9abb8d34705578c32df75689' 
  AND token = 'Ys+CnI0rTePvVXXQV2xyBlJo+5FGKGNqoMve6jonlbc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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