SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9cb36ae54c21922c1f1943d1113b2370756d676a36535e50f532433715d59def' 
  AND token = 'YJtSQOkdS05LDtAxPPLFzmkjUvJHb2z5Bslhl35Mtas=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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