SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5e3475781e6d90da197d41e06bb3af29bf7eb05f43dd113057494b7c40db632' 
  AND token = 'Mn0GEf5RoK7Ywjts6QJLXKMl2+xJ/wzkZihhrpgrCGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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