SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff66e7bb3957d8a16e1894598d2261a367479b6bc4255045bbc280433b17e3b4' 
  AND token = 'rszKm0ejhsABthLgRSObEfRmXbKu2UGyDbSBJx7uv/Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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