SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff9f51904879408626ce6669f21225f008ef1993c3636158bb6bf8d93b5d2b3d' 
  AND token = 'gNoC4me0hb1VtJ9iOY8iV8buxKGvI2DtwQrKeut1QDU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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