SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ef1df8509e6adebc8b3a7547da989e634ca468212c802e8bdc411a620064b00' 
  AND token = 'WKc37Po5CJfFxj5hMJOGMbHugatwMMpxdu+egR7nMnw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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