SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '44da93a38074371b3751fe2b1993b0d040e3de423485e7a7ce2ca1a88d48e5b9' 
  AND token = 'UUIjr4nW+8QOSzcQs2GTLF0nevA0pg2gaOJHvQ/1ndk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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