SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59e634d8c8508318940effb9f26622aae61144b3bcfae07fddbffb801a7c2de0' 
  AND token = '65FngUsKt/jZEsWWFBU2qUU+txUNUnvB85UovaGpv6k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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