SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a4c18d9c35b8cb47d8778a38886f6d082161df66d00c07200a517a997edbe36' 
  AND token = 'qwJwA8XOl0wUiETIGiAGkx1RCfjOVZ2ngX7Rdc+1th4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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