SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cdac9ee70832af35e1f7b16362a478289eb5dc9b38a8c2c872674c29c0c28c0' 
  AND token = '0yrbg+FHwrUK5UV+UB0mZPA5P1t1txxyBrCY/1eyXeI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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