SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fd8a20482189b5a2bbefd35f0bbda212d44f3be6a7d5923148b7ff692b7319f' 
  AND token = 'MXOjc+FvZ3xFawxce20R6vZT09JHnmuk8qyNon9TP+E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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