SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b3da50e55d6abebfe7debac8339b29ca0d65f691cf45bbddd66d53167fe78b9' 
  AND token = '36Q/7WLhOAQzpwrit2gHqVS10uxPBZOSgMKz+o+Ytcc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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