SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db51de83b0b6724d965c056aa338d92601ab25cbee11f0b1c570c96c516d89bc' 
  AND token = 'JZSkhPMCaKfYmjj+shWDwnwAsCAaYUvKjLnYibuRP4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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