SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fde40e6f96330910daa689269f0f271a1bbd95978fa1c1246a5503d1dacf0ea' 
  AND token = 'l5daQkMZA5j2vzwepNWQPLQRqxon3cRwVcBYevQPOE4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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