SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '597b336659c694435c739fd8833ebbf27daafb2356fbc7c28671a780aff77c4b' 
  AND token = 'RCvujT7uR+Ht0KJWWsbqUQTBAkHnPr1b8gbQvxYk2CA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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