SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e956b3d49a12df58bc7c817da7ccd3429e33b55133139ce9e2d06036845c6ba' 
  AND token = '6pWu4z1MN4i/G+pJBE7FsjCCG52Oz+JguSBnhwKnqfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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