SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '206a687d61f4a58a65bfbc33084220de0bddc630919a18ee33581f8b4cb16fde' 
  AND token = 'h8FKqTysqQDBNiq0ZJLqN50eqQRMdwEkeKLUQkGfxeE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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