SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6a377df73f5854c10ab374dd8e3bd174697efb976c53003fda8d48b54c8a14d' 
  AND token = 'JrCdqcL2A3ouc+lsWrAEt2WxYUrq0mFaqX+zXSzDRDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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