SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd869a7f4006a61c857092855bae33694912eaca98b0790c0825cb7c5d8588c75' 
  AND token = 'n9+VymJyGOSiEty7sUmQ3Immoq99nUaJ5DD1UyB0TMI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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