SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '384abd27b3228d36cc91b72824c560d64461ca57484fc08e3de4b2f14f6f86fc' 
  AND token = '6WALVaYdlxntRteI3S5zKGMAr4u+6jlRdsKWmIaxJqA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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