SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4280a0fa5df78f1603b8ced9531b1d4363c5fce2bd935862da79682d30edfd7' 
  AND token = 'Cq7zOfP0q9ehTKAjl+UkY5fmRFxTn2x5qt/JZNPnBr0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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