SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a905aabb3af4186ed894fbf2fd542066404f7fd00bfdd7e1308933a826289f29' 
  AND token = 'iMOsNedreH9JBF1qX7u9waiPNZt0MK7J8AKYqQdiMY4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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