SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2dbdd2d5dbe4cd002fbbe833017a9411f806346001ff9e759c93ab141169d82a' 
  AND token = '+NklWATCuDa9XPdCpW2NqPDuDVG9ldDLozwHfE6qxuw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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