SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c3ca783608af01a89a3961d47fa8db305f4203d161df599cd5e7d17d2b45845' 
  AND token = 'wmmsOiCxgBTfakVCRJSRJ5lvxdBiZ2Xm/NPsOj4TQnA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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