SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d6a567c8e37f932839a12157df0ab5d4490e2b6394503d52031057fdbe138e9' 
  AND token = '2TU8jjz0i20E+VJZumnPgYSjJ7EyBxmHTGfSOkf/VO0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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