SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54303f34c393581ac3652f55610c51100b10e8ca8e4642ede7004c91214b473c' 
  AND token = 'Vn9AXSTlyFVZ/rSbI5F2aKZ85ya76YEu3CZn0LWkqkw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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