SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da1b201548f32969e11468a6a5b2204a2f62be8332cffada0eda63456f598bea' 
  AND token = 'PDwboD9Gm90wODiTx0CkkZwoqSRDQcWoF9Jys2qAHus=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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