SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84f4441a65287343896af51981c1e1dd517b3cd7083ebf8b0bc02f0dfd7fa6f6' 
  AND token = 'g+GEAMEZzCeeyUdhQ26tgpnpxjpYSTDcu2wtT7dp2nI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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