SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd510a385abb121e6a009e44a9c38e24c4b81931b5b2794ddb86be6a0b7603892' 
  AND token = 'V4s/vICLrODvYG8qYKjwLHQyFEz5NqWHEMCV3uODtFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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