SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'a6abbc029543b22154673b3a91827050da59da8cd63330727b1a914651b54bd2' 
  AND token = 'LVlQLnM8xxxjKUT5JP9TVNqRxv/ShNgZJuKkY9KiDrI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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