SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef85a612f8018fcb3dd499a064f23ff63b793669018d8e3cce274d7985457424' 
  AND token = 'xiogwGMnv8QqEqW//qpRh2aQap+3YhE9D21Hm9c2/Ag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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