SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '328c8c7942b4ff827c4e5c58150e72a659c5519a49911b678c74844da2efb65a' 
  AND token = 'p4mWuNS8taLqfm4Wwa586Unx6fN41BumkQfMRdOaiu4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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