SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23ddfa6034a0bbc6569a172b2cf7ee90257c593c57ace24577d8422a29e70d76' 
  AND token = '7Tket+nsKcONtzIg65+kVMfjh6gHTLeWviZkOfZuDwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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