SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29eb24583818dc9020052d967fd741b2bbf1e1a1ce3efca168f0af0db67c238d' 
  AND token = 'uMWahm0ZZwy0jdk6wjrO6YVgXD5rHQmcpuTtAcc0WzM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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