SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db5c08c1c708d266658f249d83c158c7eaa151656a058a9efb34f006a95d384c' 
  AND token = 'nDPY7JsTPKFi8qWm9UonRXM6wwnYw2ItlDLQvBdVzeQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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