SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '679c1b6f54b675ee316021ceb9736045f8b6ffe4214737234c99fda583c1ee2b' 
  AND token = 'ga3LnK0FvdW08hwwGwhc4glu55IhpMLOkJfxTSrKl34=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}