SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5e6b27964fb696c609ba20a19bd7136a75e2f97358bfad3c30a590e383e281a' 
  AND token = '8NKt/x+EsnZypefyTYpKLGc+bWNydvOhFa9dGWAbt2U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}