SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a4fae05799fe0d886f456bca5c05283985b766728ee5c4a4ff8612675583245' 
  AND token = '/Rc1COABV0oeEQKCCBRaU0gt3ahmSmBQ+kUNKcdtNUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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